Mysterious dinosaur skeleton thought to be a teenage T. rex is actually a rival species, researchers say

Scientists have long puzzled over the origins of a mysterious dinosaur excavated in the 1940s: Was it a young T. rex or another type of dinosaur?

At first, researchers had only a tyrannosaur skull to go by, making it hard to tell if it belonged to a child or adult. Another skull and skeleton nicknamed Jane added to the debate, but didn't settle the controversy.

Now, a research team says new evidence resolves the case. The latest clue comes from a complete skeleton — first uncovered in Montana in 2006 — that scientists say identifies the mystery reptile as its own species and not a juvenile Tyrannosaurus rex.

The discovery "rewrites decades of research on Earth's most famous predator," said study co-author Lindsay Zanno with the North Carolina Museum of Natural Sciences and North Carolin